Error: Unable to find symbolic solution

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Sabrina Garland
Sabrina Garland 2021년 10월 24일
댓글: Sabrina Garland 2021년 10월 24일
syms y(x)
ode= diff(y, x)== (-(5*y)/(2*x))/(1- ((1/(2*x))^2)*((y/(1-y))^(3/5)));
cond = y(1/2)==1/2;
ySol(x) = dsolve(ode, cond)
Warning: Unable to find symbolic solution
> In dsolve (line 209) ySol(x) = [ empty sym ]
What am I doing wrong? Please Help
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John D'Errico
John D'Errico 2021년 10월 24일
편집: John D'Errico 2021년 10월 24일
  1. Just because you want it to happen, symbolic solutions need not always exist for all problems. In fact, it is a vanishingly small number of problems with symbolic solutions.
  2. You can always use a numerical solver, perhaps ODE45 might be a good place to start. It will probably fail, because at y(1/2) == 1/2, there is a derivative singularity.
  3. Finally, sometimes a solution can be found by a clever transformation of the problem. This is why they pay the mathematicians the big bucks. (Yeah, right. Like that often happens.) Ok, the good mathematicians.
  4. The derivative singularity at y(1/2) == 1/2 may suggest a good transformation may exist, but you would need to be creative.
Ok, do you want something a bit more useful? If I had to guess, no explicit solution probably exists. The result is going to exist, if at all, as an implicit function.
Sabrina Garland
Sabrina Garland 2021년 10월 24일

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